Biological indicators of disturbance at a dredged-material disposal site in Liverpool Bay, UK: an assessment using time-series data

The development of reliable indicators of disturbance in the marine environment is essential because of increasing anthropogenic pressures and the need for more effective regulation. Our objective was to evaluate 13 nationally and internationally recommended metrics, using a large dataset derived from annual (1996-2003) macro-invertebrate infaunal surveys of a Liverpool Bay dredged-material disposal site. The primary and derived univariate metrics, along with multivariate derivations, were assessed and scored against six selection criteria. Metrics that did not correlate with the pressure indicator ( the annual quantity of material disposed of) were discounted from further analysis. Of the 13 metrics evaluated, only measures of species number and Margalef's species richness index were significantly correlated. Although assemblage types were significantly different between stations, common time patterns were observed, indicating that underlying larger scale, low-frequency events may have influenced assemblage development at all locations.